package com.zsl.controller;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URLEncoder;
import java.util.List;


public class FileController extends HttpServlet {
    private static final long serialVersionUID = 1L;

    // 上传文件存储目录
    private static final String UPLOAD_DIRECTORY = "upload";

    // 上传配置
    private static final int MEMORY_THRESHOLD = 1024 * 1024 * 3;  // 3MB
    private static final int MAX_FILE_SIZE = 1024 * 1024 * 40; // 40MB
    private static final int MAX_REQUEST_SIZE = 1024 * 1024 * 50; // 50MB

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        //获取操作参数
        String service = request.getParameter("service");
        System.out.println(service);
        if ("upload".equals(service)) {
            uploadFile(request, response);
        } else if ("download".equals(service)) {
            downloadFile(request, response);
        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }

    //上传文件保存的路径是临时的
    //在重新部署项目的时候文件会消失
    protected void uploadFile(HttpServletRequest request,
                              HttpServletResponse response) throws IOException, ServletException {
        // 检测是否为多媒体上传
        if (!ServletFileUpload.isMultipartContent(request)) {
            // 如果不是则停止
            PrintWriter writer = response.getWriter();
            writer.println("Error: 表单必须包含 enctype=multipart/form-data");
            writer.flush();
            return;
        }
        // 配置上传参数
        DiskFileItemFactory factory = new DiskFileItemFactory();
        // 设置内存临界值 - 超过后将产生临时文件并存储于临时目录中
        factory.setSizeThreshold(MEMORY_THRESHOLD);
        // 设置临时存储目录
        factory.setRepository(new File(System.getProperty("java.io.tmpdir")));

        ServletFileUpload upload = new ServletFileUpload(factory);
        // 设置最大文件上传值
        upload.setFileSizeMax(MAX_FILE_SIZE);
        // 设置最大请求值 (包含文件和表单数据)
        upload.setSizeMax(MAX_REQUEST_SIZE);
        // 中文处理
        upload.setHeaderEncoding("UTF-8");
        // 构造临时路径来存储上传的文件
        // 这个路径相对当前应用的目录
        String uploadPath = request.getServletContext().getRealPath("./") + UPLOAD_DIRECTORY;
//        System.out.println(uploadPath);
//        System.out.println(request.getServletContext().getRealPath("./"));
//        System.out.println(File.separator);
//        System.out.println(UPLOAD_DIRECTORY);
        // 如果目录不存在则创建
        File uploadDir = new File(uploadPath);
        if (!uploadDir.exists()) {
            uploadDir.mkdir();
        }

        try {
            // 解析请求的内容提取文件数据
            @SuppressWarnings("unchecked")
            List<FileItem> formItems = upload.parseRequest(request);

            if (formItems != null && ((List<?>) formItems).size() > 0) {
                // 迭代表单数据
                for (FileItem item : formItems) {
                    // 处理不在表单中的字段
                    if (!item.isFormField()) {
                        String fileName = new File(item.getName()).getName();
                        String filePath = uploadPath + File.separator + fileName;
                        File storeFile = new File(filePath);
                        // 在控制台输出文件的上传路径
                        System.out.println(filePath);
                        // 保存文件到硬盘
                        item.write(storeFile);
                        request.setAttribute("message",
                                "文件上传成功!");
                    }
                }
            }
        } catch (Exception ex) {
            request.setAttribute("message",
                    "错误信息: " + ex.getMessage());
        }
    }

    protected void downloadFile(HttpServletRequest request, HttpServletResponse response) throws IOException {
        //获取目录
        String uploadPath = request.getServletContext().getRealPath("./") + UPLOAD_DIRECTORY;
        //这里默认只下载这个文件
        String fileName = "m003.jpg";
        System.out.println(uploadPath + File.separator + fileName);
        File f = new File(uploadPath + File.separator + fileName);
        if (f.exists()) {
            FileInputStream fis = new FileInputStream(f);
            String filename = URLEncoder.encode(f.getName(), "utf-8"); //解决中文文件名下载后乱码的问题
            byte[] b = new byte[fis.available()];
            fis.read(b);
            response.setCharacterEncoding("utf-8");
            response.setHeader("Content-Disposition", "attachment; filename=" + filename + "");
            //获取响应报文输出流对象
            ServletOutputStream out = response.getOutputStream();
            //输出
            out.write(b);
            out.flush();
            out.close();
        }
    }
}
